In photovoltaics and flexible electronics applications, two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs) are often subjected to mechanical strain arising from materials processing, device functioning, and thermal expansion. Here we report for the first time a study of the band gap response to uniaxial tensile strain in thin 2D HOIP flakes with a general formula of (CH3(CH2)3NH3)2(CH3-NH3)n-1PbnI3n+1. At large n (n > 3), the band gap will increase as the strain increases, and the strain response of band gap can be as high as 13.3 meV/% for n = 5, which is due to the rotation of the inorganic [PbI6]4- octahedra and the consequential Pb-I bond stretching and increase of Pb-I-Pb. Our findings provide a route to engineer the electronic properties of 2D HOIPs. The observed band gap-strain relationship can be harnessed to map the local mechanical strain in 2D HOIP-based devices and allow 2D HOIPs for sensing applications.
ASJC Scopus subject areas
- Chemistry (miscellaneous)
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology
- Materials Chemistry